The synchronous firing of dense and strongly ionized plasmas with the time structure of bunched and energetic multicharged ion beams allows us to probe, for the first time, the long searched for enhanced plasma stopping and enhanced projectile charge at the target exit.Correlated ion stopping of charged debris resulting from the fragmentation of energetic cluster ions focusing on Au foam converters is considered for indirectly driving a thermonuclear capsule. The one-dimensional (1D) simulation of converter time evolution demonstrates a very high conversion efficiency of projectile energy into hard x-ray photons building up a very hot (T-r > 300 eV) thermal bath. Intense and energetic cluster ion beams thus demonstrate considerable potential as a novel driver for inertial confinement fusion.

The stopping power of iodine ions traversing a windowless hydrogen target has been measured varying the gas in a large pressure range (10−1–120Torr). Experimental measurements present the energy losses and the charge distributions of emerging ions. Incident energies of iodine ion beams correspond to a domain where high-velocity approximation is valid. Stopping range extends up to 70% of the incident energy. Those results enable us to test stopping power theories at high velocity and large perturbation parameter Z/V. Higher-order correction terms for the stopping, calculated with point-like approximation for the charge or with more realistic atomic potential are compared with experimental energy losses.

Accurate measurements of the energy loss of chlorine ions at 1.5MeV/a.m.u. passing through a fully ionized plasma target, were achieved using a split-pole magnet at the Tandem accelerator facility at the “Institut de Physique Nucléaire”. The plasma is created by a linear wall stabilized discharge in deuterium gas. The split-pole magnet is a refocusing magnet which has an energy resolution of 3×10−4 for a large angular acceptance (±4mrad). Experimental uncertainties arising from the plasma lens effect can be avoided by using this experimental device. We have measured energy loss for Clq+, where q+ denotes the exciting charge state after interaction (q=11–15), in a cold gas and a plasma target. A clear experimental dependence of energy loss with charge state is observed.

The synchronous firing of dense and strongly ionized plasmas with the time structure of bunched and energetic multicharged ion beams allows to probe for the first time, the long searched enhanced plasma stopping and the enhanced projectile charge at target exit, as well.

Charge transfer of 4.3 MeV/u chlorine ions passing through a discharge plasma target is used as a probe to determine the plasma density and the ratio of impurities inside the plasma column. Charge-state distributions of 2 MeV/u chlorine ions passing through the plasma are then measured and compared to corresponding measurements in the cold gas. Stopping power measurements are also performed in both cases.

Clear experimental evidence of plasma stripping enhancement for chlorine ions in the MeV/u energy range is contrasted to its cold gas homologue at the same density. The velocity dependence of the charge distribution is modelled both in cold gas and in plasma experiments. Calculations are found to be in good agreement with the hypothesis of strongly reduced capture in the plasma case.

The influence of dielectronic recombination (DR) on the charge state and energy loss of fast heavy ions flowing through a target plasma of ICF interest is shown to be strongly modulated by the projectile deceleration. The inclusion of stopping effects prevents the appearance of an equilibrium charge, so that DR plays a far smaller role than recently advocated.

We develop a systematic comparison of equations of state computed within the three (TF, TFD and TFDW) Thomas-Fermi modellings with results obtained from the Average Atom Model. A special emphasis is laid on using the same analytic approximations for exchange, correlation and gradient corrections. Analogies and discrepancies with respect to temperature behaviour are also stressed.

We develop a systematic comparison of thermodynamical and atomic properties computed within the three (TF, TFD, and TFDW) Thomas-Fermi modellings with results obtained from the average atom model. A special emphasis is placed on using the same analytic approximations for exchange, correlation, and gradient corrections. Analogies and discrepancies with respect to temperature behaviour are also stressed.

The experimental setup developed at Orsay for studying ion beam-plasma interactions of relevance to inertial confinement fusion has been significantly improved. In this connection, the fast valves displayed on both sides of the plasma discharge play an essential role. The amount of residual gas is then reduced by a factor of 3. New and accurate results for the stopping and the effective charges of S7+ and Br6+ in the MeV/u energy range are presented.

We compute analytically the tail of the electron distribution function, including the radial and axial diffusion, in a plasma generated by an electron beam of a few keV. With this we can determine the ionization efficiency of the tail electrons in creating bulk electrons. The asymptotic behavior that results, for large axial distances, is compared with experimental data for molecular oxygen plasma.

A model describing the charge of fast heavy ions in a solid is presented here. Dynamical and density effects are taken into account. Relaxation near the surface to an equilibrium charge is calculated and the application to the desorption process is pointed out.

Various experiments on the charge state dependence of secondary ion emission from insulators have been performed recently using the heavy ion accelerators in Orsay and Darmstadt. A survey of the results is presented with the intention of exhibiting phenomenological trends over a wide range of beam parameters. The yields of certain small fragment ions ejected from organic samples depend strongly on the initial charge of the incident ions but not on their atomic number. Large molecule-specific ions show a different behaviour. Their yields increase considerably with the atomic number when the initial charge state is kept constant. This phenomenon is interpreted in terms of a depth contribution to desorption. By means of an averaging procedure, we calculated a mean interaction depth, from which contributions to desorption reach the surface. For a coronen target, this mean interaction depth ranges from 12 to 160 Å, when the target is irradiated by 1.16 MeV/n beams of Ne, Ar, and Kr having charge states from 5+ to 24+. The interaction depth, as defined in this work, increases linearly with the specific energy loss. An attempt was made to introduce the depth effect into the ion track model. The range of interaction predicted by these model calculations can not, however, reproduce the experimental observations.

A theoretical modeling of the interaction of energetic light ion beams with dense plasma targets is presented. The initial energy distribution, the energy loss and the angular dispersion of the beams are taken into account. This modeling is applied to the fast ignition by proton beams of the inertial fusion target as proposed by Roth et al. [1]. We found that the dispersion in angle of the beam imposes severe restriction on the schemes for fast ignitor using proton beams generated by laser irradiation of thin solid targets. Introduction We assist in the world, and more particularly in Europe to a rapid increase of the number of sub-picosecond high intensity laser facilities. In the last years it has been demonstrated that these lasers can generate, with a good efficiency, short bunches of energetic (1-100 MeV) light ions with a small emittance [2]. Several applications related to inertial fusion of this new ion-sources are expected to emerge in the near future: Roth et al [1] have proposed to use a laser generated high energy proton bunch to ignite an inertial fusion target, also Borghesi et al [3] have proposed a new diagnostic of inertial fusion targets using these ions sources by proton imaging. Both applications require an accurate description of the beam propagation through complex dense plasma targets. At Orsay we are currently developing a theoretical modeling and numerical simulations devoted to this problem. In this work we present the main characteristics of this model and the results for the fast-ignitor scenario. Theoretical model We can distinguish two main interactions in the transport of projectiles through a material: the interaction with the electronic medium of the material and the interaction with the nuclei of the material. The same formalism that was developed for cold targets [4] is now applied to plasmas: we use a dielectric formalism to describe the interactions of the projectile with the electrons through the dielectric function (k,w). The energy loss function (ELF) is based on a linear combination of the energy loss function (ELF) obtained by Mermin [5] for the external electrons and a GOS hydrogenlike approach for internal electrons [6], which describes properly the optical properties and the energy loss spectra of real materials: where 30th EPS Conference on Contr. Fusion and Plasma Phys., St. Petersburg, 7-11 July 2003 ECA Vol. 27A, P-3.64